I wanted a very small arduino type chip and foud out about a soic version of the attiny85v. My aim is a chip with a pull-up resistor to the reset pin. so a internal clock on 8Mhz. the fuse settings reflect this. here is my attempt at a altered hardware folder for the arduino ide. of course you cannot use the normal upload procedure and have to use icsp to program the chip because the attiny does not have a hardware UART.

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I think it's possible to get the IDE to upload using an ICSP. I tried with an ATtiny84 using IDE version 0017. It doesn't work. I think the problem has something to do with the processor name. I believe Rene Bohne got something similar to work but he had to modify and rebuild the IDE.

Have you tried uploading a Sketch to an ATtiny85 through an ICSP using the IDE? Or do you upload Sketches from the command-line?

I believe I've had the Arduino IDE working with direct upload for both AtTiny84 and AtTiny85 at some point.

If my memory serves me right, one issue was with Arduino constructing a mcu identifier not recognized by Avrdude. Knowing the identifier created by Arduino however, you can easily patch the avrdude.conf file to fix the "unknown part" issue.

I don't have my notes to verify against, but I believe this is correct (avrdude expects "t84"). There was also some tossing of ideas to patch the IDE to help with this, but I don't remember seeing anything from that make it to 0018.

Anyhow it should be possible to upload from within the IDE and even with an all empty core you're quickly up and running without having to learn new tools.

Well. I finally had some time to look into the stuff. it looks promising, but i was yelling to early. A lot of files in the core directory need to be changed to get the things working. with the above files and a bare minimum sketch i get a compile error. after removing the v behind attiny85v that was changed into acompile error in WInterrupts.c complaining that EICRA was not defined. this is true because this is not a atmega8: